generating random particles effect to an image

Hi!

I want to implement a code that generates random colored particles effect into an image, something like the attached image

'particles.jpg' . (the background will be bleck, eventually I want to create png image)

My idea is to generate random 2d gaussians (with random centers and radius), and then combining them to one image. After that I want to paint them with random colors (each of them will have different color).

can you please help me create this code?

Answer 1

[DGM]

This is built using MIMT tools:

% parameters
s = [500 300]; % output image size [height width]
numspots = 20; % number of spots
spotbounds = [30 70]; % allowable range of spot widths (px)
spotopacity = [0.1 0.7]; % allowable range of spot opacity
blurbounds = [0 50]; % allowable range of blur width (px)
bgcolor = [0.08 0 0.2]; % background color (unit-scale)

spotbounds = round(spotbounds/2); % convert to radius
s = [s(1:2) 3]; % output is color
padwidth = spotbounds(2) + blurbounds(2) + 2; % calculate required padding
wpict = colorpict([s(1:2)+padwidth*2 s(3)],bgcolor); % preallocate
for n = 1:numspots
    % create antialiased disk (the spot)
    rspot = ceil(randrange(spotbounds,[1 1]));
    spotmap = simnorm(fkgen('disk',[2 2]*rspot));
    
    % blur the spot as required
    fkb = fkgen('gaussian',randrange(blurbounds,[1 1]));
    spotmap = imfilter(spotmap,fkb,'full');
    
    % find coordinates to insert the spot
    rxy = ceil(rand([1 2]).*s(1:2))+padwidth;
    rspot = size(spotmap,1)/2;
    rangec = (rxy(1)-floor(rspot)):(rxy(1)+ceil(rspot)-1);
    ranger = (rxy(2)-floor(rspot)):(rxy(2)+ceil(rspot)-1);
    
    % composite the spot into the image
    thisalpha = randrange(spotopacity,[1 1]);
    thiscolor = rand(1,3);
    thisbg = wpict(rangec,ranger,:);
    wpict(rangec,ranger,:) = replacepixels(thiscolor,thisbg,spotmap*thisalpha);
end
outpict = imcast(cropborder(wpict,padwidth),'uint8');

imshow(outpict)

The rest is tailoring the distributions. For example:

% parameters
s = [300 500]; % output image size [height width]
numspots = 70; % number of spots
spotbounds = [15 40]; % allowable range of spot widths (px)
spotopacity = [0.1 0.7]; % allowable range of spot opacity
blurbounds = [0 50]; % allowable range of blur width (px)
bgcolor = [0.08 0 0.2]; % background color (unit-scale)

clustercenter = [1 0.5]; % cluster location in normalized coordinates [y x]
clustersigma = [0.25 0.25]; % control spread of spots away from cluster center

spotbounds = round(spotbounds/2);
s = [s(1:2) 3];

padwidth = spotbounds(2) + blurbounds(2) + 2;
wpict = colorpict([s(1:2)+padwidth*2 s(3)],bgcolor);
for n = 1:1:numspots
    % create antialiased disk (the spot)
    rspot = ceil(randrange(spotbounds,[1 1]));
    spotmap = simnorm(fkgen('disk',[2 2]*rspot));
    
    % blur the spot as required
    fkb = fkgen('gaussian',randrange(blurbounds,[1 1]));
    spotmap = imfilter(spotmap,fkb,'full');
    
    % find coordinates to insert the spot
    goodpoint = false;
    while ~goodpoint
        rxy = ceil((clustercenter + clustersigma.*randn([1 2])).*s(1:2))+padwidth;
        goodpoint = all(rxy > padwidth) && all(rxy <= padwidth+s(1:2));
    end		
    rspot = size(spotmap,1)/2;
    rangec = (rxy(1)-floor(rspot)):(rxy(1)+ceil(rspot)-1);
    ranger = (rxy(2)-floor(rspot)):(rxy(2)+ceil(rspot)-1);
    
    % composite the spot into the image
    thisalpha = randrange(spotopacity,[1 1]);
    thiscolor = rand(1,3);
    thisbg = wpict(rangec,ranger,:);
    wpict(rangec,ranger,:) = replacepixels(thiscolor,thisbg,spotmap*thisalpha);
end
outpict = imcast(cropborder(wpict,padwidth),'uint8');

[David Levi]

@DGM

thank you so much for your answer!! it is amazing!

If we are already talking about this I want to ask you something more complexd. If I may.

The purpose of this question is to create a video (10 seconds long) of moving colored particles.

something as shown in the next video:

https://www.youtube.com/watch?v=1F4Jjw93UWw&list=PLTjT1adI71CiM-EuzGqdQ_7l5JIBH7Lf-

The particles you created serves purpose. now can you help me create a video thar makes those particles move? or make them fade in/out? If yes , I willl be grateful !!

[Image Analyst]

@David Levi you can make up all the individual frames and save them to disk. Then build them into a movie. I'm attaching a few demos that show you how.

[David Levi]

@Image Analyst I appreciate your answers and efforts, but in this case I think that @DGM can be more helpful for me.

I know that I can create all the individual frames using DGM's code, but as explained before, it is needed to have a connection between those frames (fade in/out or moving particles). this is more complexed for me. please understand

[DGM]

If you want to simulate motion, then you'll have to take a step backward and separate the spot creation and positioning from the compositing. You'll have to keep track of each spot sub-image, its position/trajectory, its color and alpha between frames. If new spots are allowed to move into frame during the sequence, then it just becomes that much more complicated.

Consider the given examples as a simplified version of what you want. Some of the elements should still be useful. I don't have the time to write a whole thing. What I posted was an adaptation of something I had at hand.

I should add that if you want to simulate depth of field with the blur, you might want to scale the blur according to the spot size instead of allowing it to be independent and random like I did.

Answer 2

[Image Analyst]

Here's a start. I trust you can finish it. If so, see this:

MATLAB Academy - Free 2 hour training

% Demo by Image Analyst to create multiple Gaussians.
% Initialization Steps.
clc;    % Clear the command window.
close all;  % Close all figures (except those of imtool.)
clear;  % Erase all existing variables. Or clearvars if you want.
workspace;  % Make sure the workspace panel is showing.
format long g;
format compact;
fontSize = 20;
numSpheres = 50;
windowWidth = 30;
rows = 640;
columns = 640;
grayImage = zeros(rows, columns, 'uint8');
for k = 1 : numSpheres
    radius = windowWidth * rand;
    g = rescale(fspecial("gaussian", windowWidth, radius), 0, 1);
    g = uint8(255 * g);
    subplot(1, 2, 1);
    imshow(g, []);
    axis('on', 'image')
    caption = sprintf('One Gaussian with sigma = %.5f', radius);
    title(caption, 'FontSize', fontSize)
    xUpperLeft = round(rand(1) * (columns - windowWidth)) + 1;
    yUpperLeft = round(rand(1) * (rows - windowWidth)) + 1;
    % Paste in image
    grayImage(yUpperLeft : (yUpperLeft + windowWidth - 1), xUpperLeft : (xUpperLeft + windowWidth - 1)) = g;
    subplot(1, 2, 2);
    imshow(grayImage, []);
    axis('on', 'image')
    caption = sprintf('%d Gaussians', k);
    title(caption, 'FontSize', fontSize)
    drawnow;
end
g = gcf;
g.WindowState = 'maximized'

I'm attaching another demo, gaussianCircles_demo.m, that produces this image.